Full circle boom crane



April 2, 1957 J. ANros. Erm.

vm1. CIRCLE: BooM CRANE Filed March 13, 1951 6 Sheets-Sheet 1 Y April 2, 1957 J. ANTos ETAL FULL CIRCLE BCCM CRANE 6 Sheets-Sheet 2 Filed March 13, 1951 i 'INVENTORS sm c i' BY` M April 2, 1957 Filed March 13, 195.1

J. ANTOS ET AL -FULL CIRCLE BOOM CRANE e sheets-sheet 5 April 2, 1957 J. ANTOS ET AL v 2,787,383

FULL CIRCLE BCCM CRANE Filed March 1s., 1951 e shew-sheet 4 IN VEN TOR Jogg/ob @72255, BYIQQz/fz C 5mm/z, 1441 pril 2, 1957 J. ANTos ET AL FULL CIRCLE BOOM CRAN April 2, 1957 J. Amos ET AL L 2,787,383

FULL CIRCLE BOOM CRANE Filed March 13, 1951 6 Sheets-Sheet 6 owwl @JB/wam s? v I Nga/mum@ ML AML JNVENORS nited States Patent O FULL CIRCLE BOOM CRANE Joseph Antos and Edwin C. Brown, Aurora, lll., assignors,

by mesne assignments, to Baldwin-Lima-Hamilton Corporation, Philadelpln'a, Pa., a corporation of Pennsylvania Application March 13, 1951, Serial No. 215,322

11 Claims. (Cl. 212-35) This invention relates to improvements in a full circle boom crane capable of being attached to various types of tractors, automotive trucks, railroad cars or any xed or movable support.

The present application embodies improvements upon the construction of full circle boom crane disclosed in Patent No. 2,462,926, issued March 1, 1949 to Fred D. Wilson, Joseph Antos and I ames D. Benbow.

The general object of our invention is to provide a full circle extensible boom crane having improved means to move the boom extension inwardly Iand outwardly; to raise and lower it to wind in or pay out a load supporting ca'ble depending from the outer end of the boom extension, and to revolve the boom crane, the load through a portion of a full circle of revolution, or through one or more complete circles of revolution; and to perform said operations Iall at one time, or one operation at a time. The operators station is shown as revolving with the boom crane, but it may have stationary mounting.

Another object of our invention is to provide Iimproved lhydraulically actuated mechanism for effecting a hydraulic extension and hydraulic retraction of the boom extension, and wherein this hydraulically actuated mechanism is embodied within t'he boom extension and boom support. This hydraulically actuated mechanism is further characterized by a stationary piston with packing on both sides of the piston and a movable cylinder connected to the boom extension to move the boom outward or inward to lengthen or shorten the over-all length of the boom as desired, by admitting the oil, steam or air under pressure into the cylinder -to either side of the piston, whereby to exert pressure at either end of the cylinder to shorten or lengthen the boom as desired.

Another object of this invention is to use two tubes for the piston, having -openings in said tu'bes to permit oil, steam or air to be admitted lto either side of the piston packing torbuild up pressure on one side of the piston and release pressure on the other side of the piston, so as to move the cylinder lattached to the boom extension in the direction desired and thus shorten or lengthen the boom.

Another object of the invention is to provide the above power extended and power retracted extensible boom with a load supporting cable which winds upon a power winch operated by a hydraulic motor located at the rear end of the boom support.

Another object of this invention is to provide improved control means -adapted to control the raising 4or lowering of the cable, or to shorten or lengthen the cable during the movement of the boom extension, so that the cable hook will remain in a constant relation to the boom extension.

One preferred embodiment of our invention is illustrated in the accompanying drawings in which:

Fig. 1 is a side elevation of the full circle boom crane mounted on a truck, having outriggers with adjustable screw jacks, and showing the boom in a horizontal position, intermediate position and in a high position, with the boom extension partially extended in the high position and the cable hookup raised substantially to the boom extension.

Fig. 2 is a plan View of Fig. 1 showing the boom extension and boom support in three horizontal positions, and showing the location of `the operators seat and cont-rol valves.

Fig. 3 is the end view of Fig. 1 with the boom in the horizontal position, showing 4the Vertical location of the control valves, and also showing the outriggers with the adjustable screw jacks in position.

Fig. 4 is a cross sectional horizontal View showing the position of the Outrigger and adjustable screw jack, when the crane and truck are ready to be moved.

lFig. 5 is a longitudinal cross section of the boom crane showing the boom support and boom extension in a horizont-al position.

Fig. 6 is a partial section showing the boom support, the boom raising and lowering cylinder and the plates and pins on which the cylinder and its piston are mounteda Fig. 7 is a cross section taken on the plane of the yline 7-7 of Figure 5, showing the boom support, boom extension and two of the roller means used to support the boom extension during its movement 'between extended and retracted positions.

Fig. 8 is a cross section taken on the plane of the line 8--3 of Figure 5 showing the boom support, boom extension and the outer boom support roller.

Fig. 9 is ya diagrammatic view showing the hydraulic system used to raise, lower, and to move the boom extension inward and outward, and to wind in and pay out the load supporting cable, together with the hydraulic pump, oil tank, piping and control Valves.

rFig. l0 is a fragmentary longitudinal section on a larger scale of the inner end of the boom extending and retracting cylinder and piston shown in Fig. 5.

Figure l1 is a fragmentary longitudinal section of the extensible boom and hydraulic ram on an enlarged scale, showing in greater detail the swivel connection therebetween which permits tilting between the boom extension and ram. v

Figure 12 is a transverse sectional View taken on the plane of the line 12-12 of Figures 5 and 1l.

Fig. 13 is an enlarged View of the outer end of the ram showing the piston cups and ram cylinders, and

Fig. 14 is an enlarged detail section of the pivotal connect-ion between the anchor bracket and the inner end of the piston rod of the boom ram.

Referring to Figs. l, 2 and 3, we have shown the rotatable hydraulic crane 3 having a stationary support 4 lof conical or cylindrical shape mounted on the rear of truck 1 between the dual axles and wheels 2. Said conically-shaped support 4 is attached to `a plate 5 by bolts or -rivets 6 '(shown in Figure 5), and plate 5 in turn is `bolted to truck frame 1 by bolts 7.

A turntable member 8 of conical or cylindrical shape, to which the rotatable hydraulic crane 3 is attached, is supported for rotation by upper and lower roller bearings 9 mounted between the conical support 4 and the conical turntable member 8, see Fig. 5.

Vertical plates lil and 11, one on each side of conical support member 8, are bolted thereto by bolts 12. See Figs. 1, 2, 3 and 5.

A vertical two way hydraulic cylinder 13 is supported at the bottom for oscillation about a horizontal pin 15 which in turn passes through the vertical plates 10 and 11.

. `Piston rod 14 carries a piston 16, and inlets 17 and 18 are provided .at the top and bottom of cylinder 13 to permit oil, steam or 'air under pressure to raise and ICC lower the piston rod 14 and piston 16 as desired.

The upper end of the piston rod 14 is connected to a boom support 20 by a horizontal pin 19 to permit the raising and lowering of boom support 20 about a hinge pin 21 which extends through plates 10 and 11 to tiltably mount the boom support 20 at 22, whereby the boom support 20 can `be raised and lowered by the piston 16 and piston rod 14 (see Figs. 5 and 6). The boom support 20 is, for the major portion of its length, -of substantially rectangular cross section.

The `extensible boom 23, made of plates rectangular in shape, telescopes almost its entire length into the rectangular boom support 20 and moves outwardly and inwardly thereof on lower rollers 24 and 2S carried by the boom support, being further guided by an upper inner roller 26 to prevent tilting of the inner end of boom extension 23 when the crane is lifting a load at the outer end of boom extension 23, these rollers being supported by both sides of the boom support 20, as shown in Figs. 5, 7 and 8. The roller 25 rotates on an eccentrically mounted journal pin 25' (Figure 7), by the adjustable rotation of which the axis of the roller 25 can be adjusted upwardly or downwardly so that the boom extension 7.3 will have a snug rolling t with the upper inner roller 26.

Telescoping its entire length within the extensible boom 23 is the boom operating ram, which is made up of three tubes 27, 2S and 29, as shown in Figs. 5, 7 and `9-12. The inner tube 27 constitutes a tubular piston rod, the intermediate tube 28 constitutes a huid conducting tube surrounding the piston rod, and the outer tube 29 constitutes the movable hydraulic cylinder for extending and retracting the boom extension 23. As clearly shown in Figures and 7, the upper and lower walls of the rectangularly shaped hollow boom extension 23 are substantially spaced from the hydraulic ram cylinder 29 so as to provide a vertical clearance space s therebetween. By virtue of this clearance space s, the outer end of the extended boom can have a considerable degree of downward exure under heavy load, without causing any binding action on the hydraulic ram 27-29. To this same end, the hydraulic ram 27--29 has a oating mounting in this clearance space s on two longitudinally spaced points of support, one of which is a pivot at the rear end of the tubular piston rod 27, and the other of which is a thrust transmitting swivel located intermediate the ends of the ram cylinder 29, the latter of which will now be described.

AAt the approximate center of the outside of tube 29 are welded two circular rings 30 and 31 and in between these circular rings 30 and 31 -is a thrust transmitting yoke or swivel member 32 having holes 33 yat the top and bottom for receiving top and bottom pins 34. These pins 34 extend through member 32 and through bosses 35 carried by the vertical outside plates of the boom extension 23, the projecting ends of these pins 34 receiving transverse retaining pins 36 (Figure 12). In this manner, the hydraulic cylinder tube 29, the thrust transmitting member 32 and the boom extension 23 are caused to move together during the outward and inward movement of the hydraulic cylinder tube 29. As Shown in Figure 1l, the 'bore in the yoke or swivel member 32 through which the ram cylinder 29 passes has a relatively loose tit over the cylinder to accommodate relative tilting motion between the yoke member and cylinder. For example, this bore in the yoke member tapers outwardly with an expanding taper 32 in each direction from the transverse center line of the yoke member, thereby accommodating a substantial `degree of vertical tilting motion of the ram cylinder 29 relatively to the yoke member 32, so that downward deection of the fully extended 'boom extension 23 under heavy load will cause no bending effect on the cylinder 29- and no binding action between the cylinder and piston. The location of the swivel yoke 32-substantial1y midway between the ends of the cylinder 29 is also. an

important feature because it places the point of swiveling substantially at the center of gravity of the cylinder, and thus reduces the downward or sagging load stresses acting on the cylinder `and piston, particularly when the boom extension 23 is fully extended.

The inner tube 27 and intermediate tube 28 are connected together at the rear and front ends by welding circular separators 37 and 37A to both tubes.

The intermediate tube 28 at its inner end has a hole 3S drilled at the top and a boss 39 welded thereto, drilled and tapped for a tlexible hose connection 103 to permit the oil, steam or air under pressure to ow into the space between the intermediate tube 28 and inner tube 27, and thence pass through holes 38A at the forward end of intermediate tube 28 to exert pressure between the inner piston cup 40 and follower 41 and a closure head member 52 at the inner end of cylinder 29, whereby to cause the boom extension 23 to move inwardly on the rollers 24, 25 and 26. The inner tube 27 is tapped at 42 at its inner end for a flexible hose connection 102 to permit oil', steam or air under pressure to ilow through the tubular piston rod 27' to the forward end ofl the cylinder tube 29 and exert pressure between the outer piston cup 43 and follower 44 and a closure head 48 closing the outer end of the cylinder, whereby to cause the boom extension 23 to move outwardly on rollers 24, 25 and 26.

The piston cups 40 and 43 are separated by spacer 45 and are. held together as one unit by two nuts 46 and 47 on the outer end of inner tube 27. As above described, the forward end of the outer tube 29 has a circular closure head or cap 48 welded thereto to close this outer end of the cylinder.

At the inner end of the boom support 20 and mounted onV pin 21 is an anchor bracket 55 having a circular ring portion to fit over the outer end of the tubular piston rod 27 to support and hold this tube 27 against endwise movement. As shown` in Figure 14, thev separator 37 which separates the rear ends of inner tube 27 and intermediate tube 28` is welded to both of these tubes, and formed at the rear end of said separator is a spherically shaped seating surface 37b. This surface 37b seats in a matching spherically shaped socket 551: which is formed in the front end of the bore 55C of ring portion 55. Bore 55C has ay rather loose tit over the inner tube 27; as, for example, by expanding the rear end of said bore outwardly into a counterbore 55d. Thus, relative tilting movement is permitted between the inner tube 27 and the anchor bracket ring portion 55 around the axis of. the spherical seatingy surfaces 37b and 55b. The rear end of inner tube 27 is threaded for receiving two nuts 56 betweenwhich is confined a lock plate 56. This lock plate 56' engages a flat surfaceV on the end `of the tube 27 and also engagestthe. anchor bracket 551er boom support 20, so as to prevent the inner tube 27 from rotating axially. The nuts 561are backed off from a tight fit against the end of ring portion 55 so as to permit the above described tilting movement at the spherically shaped seating surfaces 37b and 55b. From the foregoing, itwill be seen that the boom ram 27-29 has a vertically swiveling floating mounting between the yoke member 32 supporting the cylinder 29, and the. spherical seating surfaces37b, 55b supporting the rear end' ofthe piston rod tube 27. Hence, the outer end of the extensible boom 23'can flex downwardly under heavy loads without causing resultant binding action inthe hydraulic ram 27g-29.

The inner end of the outer cylinder tube 29 has a circular member or boltingange 49 welded around the outside, this flange having a plurality. of spaced holes 50 drilled and tapped for stud bolts 51. Attached thereto is a rear cylinder head 524 comprising a` closure: member which is insertedV inside of outer cylinder tube 29, and which isheld in` position atir theA rear ofthe cylinder by nuts 53 on studs 5I. Thisrre'a'r cylinder head* 52 has an axial bore 54 having a sliding fit over the intermediate uid conducting tube Z8, and this bore is nished and provided with felt and leather wipers 57 held in place by spring retainers 57 to retain the oil, steam or air in the cylinder tube 29 during the movement of cylinder tube 29 and closure head 52 along the intermediate tube 28, during the operations of moving the cylinder 29 inwardly or outwardly to retract or extend the boom eX- tension 23 to suit the conditions desired.

Attached to the outside rear portion of the boom support 20 is a vane type hydraulic reversible motor 58 which rotates a worm 59 that in turn rotates worm gear 60 in a self-locking drive (Figure 9). The latter is attached to a cable drum 61 which is mounted on the rear end 62 of the boom support 20, and to which cable drum is attached a cable 63.

At the forward end of boom extension 23 are mounted two or more cable sheaves 64 which rotate on pin 65. The cable 63 is reeved over the sheaves 64 and over a plurality of sheaves or pulleys 67 pivoted on pin 65A of a suspended sheave block 66, the latter carrying a swiveled cable hook 68. The end of the cable 63 is dead-ended to the sheave block 66 at 69, or to any other desired point of attachment.

Mounted on the plate which carries the turntable member 8 is an oil, steam or air dual reciprocating engine 70 (Figure 9) which rotates the gear 71 and transmits a drive through intermediate gear 71A to a ring gear 72 attached to the outside circumference of the turntable member 8 to rotate the crane and all of its parts in either direction through a full circle or any part of a circle.

Attention is now directed to the diagrammatic view of the operators control valve assembly 76 as shown in Figure 9, including the piping and other parts of the hydraulic system used in raising and lowering and extending and retracting the boom extension 23, operating the cable 63, and rotating the boom crane. A hydraulic pump S1 is mounted on the truck 1 and is driven from the power takeoff 82 of the truck 1. An oil reservoir tank '63 is mounted on the truck 1 and is connected to oil pump 81 by pipe 84. A pressure relief valve 85 is located between the oil pump 81 and a rotatable liquid distributing head 86-87 which is disposed coaxially of the axis of rotation of the turntable 8. The outer sleeve 87 of this liquid distributor is fastened between the plates 1t) and 11 so as to rotate with the boo-m crane, and the inner core member 86 is attached to and remains stationary with the conical support 4 which is attached to the truck 1, las shown in Fig. 5.

Referring to Figs. l, 21and 3, the operators station 73 is shown as being made up of two plates 74 and 75, which are attached to side plate 1t) or adjacent portions of the rotatable turntable structure so that the operators station revolves directly with the turntable and boom crane. form the back, floor and front of the operators station and is attached to plate by bolts, rivets or welding. Plate 75 forms the side of the operators station and is attached to plate '74 by bolts, rivets or welding. The operators seat 77 is attached to plates 74, 75 and 10. The operators control valve assembly 76 is mounted on a support attached to plates 74, 75 and 10 directly in front of the operators seat.

The oil pump 81 pumps the oil from oil tank 83 through pressure relief valve S5 and thence through line Plate 74 (Figure 3) is formed in a U shape to V 88 to distributing core element 86. From this distribut- `6 99 which have three positions, viz: vertical which is neutral; push forward for one direction of operation; and pull backward for the opposite direction of operation.

The four valves 92, 93, 94 and 95 are bolted together and oil ows in a manifold space communicating with each valve and affording pressure at each valve, thereby permitting the operation of a single valve or any combination of valves at one time. Attention is directed to the aforementioned Patent 2,462,926 for the disclosure of certain details of the control valves 92-95 dual reciprocating engine 70 Iand other parts of the hydraulic system which we preferably employ in the present invention.

By pushing valve lever 99 forward, oil under pressure will flow from valve 95 through pipe or hose 100 to inlet 18 of the cylinder 13, thereby causing the piston 16 and piston rod 14 to move upwardly in cylinder 13 for ktransmitting upward thrust to the horizontal pin 19 so as to raise the boom support 20 and boom extension 23 about horizontal hinge pin 21.

Upon returning valve lever 99 to neutral or vertical position, the boom support 20 and boom extension 23 will remain in the raised position. By pulling back wardly on the valve lever 99 the oil under pressure will be caused to ow from valve 95 through pipe or hose 101 to inlet 17 of cylinder 13. This will cause the piston rod 14 and piston 16 to move downwardly and cause the oil on the underside of piston 16 to ow through connection 18 and pipe or hose 100 to the valve 95 and thence through connections 79, 90, 87, 86 and 91 back to the oil reservoir 83, thus permitting the boom support 20 4and boom extension 23 to return to the horizontal position. If desired, the boom support 20 and boom extension 23 can be held in any intermediate position by returning valve handle 99 to the vertical or neutral posi tion, which thus maintains equal pressures on both sides of the piston 16.

By pushing forwardly on valve lever 98 of valve 94, the oil under pressure will flow from valve 94 through pipe or hose 102 to the inner end of the tubular piston rod tube 27 and thence forwardly through the tube 27 to the cylinder space between the circular end cap 43 and the piston cup 43 and follower 44, thereby causing the cylinder tube 29 and boom extension 23 to move outwardly in the boom support 20 on rollers 24, 25 and 26. The outward movement of the boom extension 23 can be stopped at any point by returning the valve lever 98 to neutral position.

By pulling rearwardly on valve lever 98 of valve 94, the oil under pressure will flow through pipe or hose 103 to the inner end of intermediate iluid conducting tube 23 through hole 38 into the annular space between the inner tube 27 and intermediate tube 28. From this annular space the fluid will flow outwardly through the four holes 38A in the forward end of intermediate tube 28 into the cylinder space between intermediate tube 2S and outer tube 29 and thus apply pressure between the rear cylinder head 52 and the piston follower 41 and piston cup 40, whereby to cause inward movement of the boom extension 23. In each of these outward and inward movements of the boom extension 23, the oil in the discharging or non-pressure end of the cylinder 29 is returned to the oil reservoir 83.

By pushing or pulling movement of valve lever 98, the boom extension 23 can be quickly shifted to any desired position,`and by placing the valve lever 98 in neutral position, the boom extension can be positively held in any such desired position.

The raising and lowering of the cable 63 and hook 68 is controlled by valve 93. By pulling rearwardly on valve lever 97 of valve 93, the oil under pressure will ilow through pipe or hose 10S to the vane type motor 58 which rotates Worm 59, worm gear 60 and cable drum 61 to raise the cable 63 and cable hook 68.

By :pushing forwardly on valve lever 97, the direction of the vane type 4motor 58 will be reversed, land cable 63 and cable hook 68 will be lowered. By putting the valve 'lever 97 in neutral position, the operator can hold lthe position ofthe cable 63 and cable hook 68. vThe `worm 59 and worm wheel 60 may be proportioned to form an irreversible drive, yif desired. If -a drain for the vane type motor '58 is desired, a separate li-ne 106 will ret-urn the .oil from the motor lto distributing sleeve 87 and distributing core 86, a-nd thence through pipe or -hose 197 to the/oil tank 83.

As shown -in Figures 3 and 9, the boom extending and retracting control lever 98 and the cable Windi-ng and kunwinding control lever 97 are disposed side by side, Aand have .their handles arranged sufficiently close together so that .both Ycont-rol lever handles may be covered by the span of one hand -of the operator. Thus, when the operator ldesires to extend the extensible boom 23, without the possibility of the Isuspended .sheave `block 66 or cable hook 68 becoming fouled in the head sheave 64, 11e pushes forwardly on both Acontrol levers 97 and 98 simultaneously. The forward movement of the Vcontrol lever 98 extends the boom extension 23, andthe forward movement of the control lever 97 pays out cable from the cable ldrum .611, thus preventing the suspended sheave block 66 or cable hook 68 from being drawn up into position where it might become fouled in -the .head sheave 64. This dual control through the two control levers 97 and 98 may also be employed to 'prevent the cable from elevating the load unduly relatively to the boom, in the oper-ation of extending the boom. Conversely, when the operator desires to retract the extensible boom 23, without causing the cable to lower the load unduly `relatively to the boom, he lpulls rearwardly on both control levers simultaneously. The rearward movement of the control lever 98 retracts the boom extension 23, and the rearward movement of the control lever -97 winds up cable on the drum 61, thus preventing the cable hook 68 from being lowered objectionably by the act of retracting the boom. By having the two control levers 97 and 98 disposed side by side, and sufiiciently -close together so that they can both be covered or grasped in 4the -span of one hand of the operator, the operator can perform either of the above described dual operations of vcontrolling the boom and controlling the cable solely through the use of one hand thus leaving the other hand :free vfor performing other operations, such as yfor concurrently actuating the control lever 96 for swinging the turntable mounting or for concurrently `actuating the control lever 99 for raising and .lowering the boom.

To leffect the horizontal rotation of the crane in either direction, and to hold Vit in 'any desired position, 4the valve 92 is provided. To rotate the crane to the right, a 'forward push on valve Vlever 96 of valve 92 will lcause the oil under pressure to flow through pipe or hose 103 to distributing sleeve 87 and distributing core 86, and thence through pipe or hose 110 2tothe dual reciprocating engine 70 in such direction as to rotate gear 71 and gear teeth 72 attached to 'the conical support 4 in `the appropriate direction for rotating the vcrane to the right.

To rotate the crane to the left, a rearward pull on the lever 96 will cause the oil to flow under pressure 'through pipe or hose 109 to distributing sleeve 87 and distributing core 86, .and thence through pipe or hose 111 to the dual reciprocating engine 7), so as to rotate gear 71 and gear teeth 72 attached to kconical support in the appropriate direction for rotating the crane to the left. The crane can be held in any desired position |by placing valve lever 96 in neutral position. In each of these operations of the dual reciprocating engine 70, the non-pressure or discharge side of each cylinder .returns the oil to the tank 83, :as fully disclosed in the above-mentioned Patent 2,462,926.

To give `the vehicle greater lateral stability when the lboom crane is .swinging loads `to one side or the other of the vehicle, we provide outriggers .and .adjustable vjacks 80 at the four corners of the rear -portion of the vehicle frame (Figures 2, 3 and 4). These outriggcrs and adjustable jacks comprise conventional ybase plates 30a from which rise adjustable screw jacks Sb that are pivotally connect-ed vatftiic to slidable struts 80d. These struts are mounted for inward and outward sliding movement in transverse guide channels 89e carried Iby or constituting lpart-of the vehicle frame. In Figure 4 we have illustrated how these Outrigger jacks can be swung upwardly and slid inwardly into retracted position in the guide channels 80e, where they are completely out of the way when the vehicle is travelling.

`From the foregoing description it will be readily seen that we have produced an improved device that substantially fullls the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred 4construction -of the device, still in practice such deviations therefrom may be resorted to as do not form a departure from the spirit of the invention, as defined -by the appended claims.

Having thus described our invention, what we claim as new and useful land desire to secure by Letters Patent is:

l. In an extensible yboom crane of the classdescribed, the combination of a boom support, a tubular boom movably carried by said boom support for outward lextending and inward retracting movement relatively thereto, a cylinder substantially enclosed within said tubular boom, swivel yoke means operatively connecting said cylinder with said boom to cause 'said boom to move endwise with said cylinder, while permitting relative swiveling movement between said cylinder and boom in a Vertical plane, said swivel yoke means being located substantially mid- Way between the ends of said cylinder so that said cylinder is substantially balanced 'fore and aft in its swiveled connection to said Iboom, piston apparatus in said cylinder comprising a piston rod having anchored attachment at its inner end to said boom support and having a piston head mounted on its outer end, and two fluid passageways associated with said piston apparatus and extending longitudinally of said piston rod, one passageway for introducing working iluid under pressure into the cylinder area on the front side of said piston head for extending the `boom outwardly, and the other passageway for introducing Working tluid under pressure into the cylinder area on the back side of said piston head for .retracting the boom inwardly.

2. In an extensible boom crane, the combination of a boom support, an extensible hollow boom Itelescoping almost its entire length into said boom support, a hydraulic ram .in said boom comprising a cylinder and piston operative to extend `and retract said boom, said cylinder reciprocating directly with said boom in its extending and retracting movement, said cylinder and piston telescoping substantially entirely into said .hollow boom when the latter is fully retracted, said piston comprising a piston rod and a piston head mounted on its outer end, two uid passageways extending longitudinally of said piston rod, one passageway for introducing working fluid under pressure into the cylinder area on the front side .of said piston head for extending the boom outwardly, the other passageway for introducing Working uid under pressure into the cylinder area on the back side of said piston ,head for retracting the boom inwardly, one of the walls of said |boom being vertically spaced from said hydraulic ram to define a vertical clearance space therebetween which will permit downward exure of `the outer end of said boom under load without causing resultant binding action on said ram, an anchoring ybracket pivotally anchoring the inner end of said piston rod to .said boom support, and swivel Vyoke means operatively vconnecting said cylinder with said 'boom to avances while permitting relative swiveling movement between said cylinder and boom in the vertical plane of said clearance space, said swivel yoke means being located substantially midway between the ends of said cylinder so that said cylinder is substantially balanced fore and aft in its swiveled connection to said boom, said anchoring bracket and said swivel yoke means providing. a floating mounting of said hydraulic ram in said vertical clearance space.

3. In an extensible boom crane, the combination of a boom support, an extensible hollow boom telescoping almost its entire length into said boom support, a hydraulic ram in said boom comprising a cylinder and piston operative to extend and retract said boom, said cylinder reciprocating directly with said boom in its extending and retracting movement, said cylinder and piston telescoping substantially entirely into said hollow boom when the latter is fully retracted, said piston comprising a piston rod and a piston head mounted on its outer end, two uid passageways extending longitudinally of said piston rod, one passageway for introducing working fluid under pressure into the cylinder area on the front side of said piston head for extending the boom outwardly, the other passageway for introducing working uid under pressure into the cylinder area on the back side of said piston head -for retracting the boom inwardly, one of the walls of said boom -being vertically spaced -from said hydraulic ram to deline a vertical clearance space therebetween which will permit downward ilexure of the outer end of said boom under load without causing resultant binding action on said ram, an anchoring bracket pivotally anchoring the inner end of said piston rod to said boom support, Iand swivel yoke means operatively connecting said cylinder with said iboorn to cause said boom to move endwise with -said cylinder, while permitting relative swiveling movement between said cylinder and boom in the vertical plane of said clearance space, said anchoring bracket and said swivel yoke means providing a oating mounting of said hydraulic ram in said vertical clearance space.

4. In an extensible boom crane, the combination of a boom support, an extensible hollow boom telescoping almost its entire length into said boom support, a hydraulic ram in said boom comprising a cylinder and pist-on operative to extend and retract said boom, said cylinder reciprocating directly with said boom in its extending and retra-cting movement, said cylinder and piston telescoping substantially entirely into said hollow boom when the latter is fully retracted, one of the walls of said boom being vertically spaced from said hydraulic ram to define a vertical clearance space ltherebetween which will permit downward exure of the outer end of said l'boom under load without causing resultant binding action on said ram, Ian anchoring bracket pivotally anchoring the inner end of said piston rod to said |hoorn support, and swivel yoke means operatively connecting said cylinder with said boom to cause said 'boom to move endwise with said cylinder, while permitting relative swiveling movement between said cylinder and yboom in the vertical plane of said clearance space, said swivel yoke means being located substantially midway between the ends of said cylinder so that said cylinder is substantially balanced fore and aft in its swiveled connection to said boom, said anchoring bracket and said swivel yoke means providing a oating mounting of said hydraulic ram in said vertical clear-ance space.

5. ln a device of the class described, a base frame, a crane frame mounted on the base frame for rotation thereon on a vertical axis, said frame having a bracket portion extending rearwardly relative to said axis, said bracket portion terminating in a pivot portion providing a pivot with a horizontal axis, a boom support mounted adjacent its rear end on said pivot land being swingable from a substantially' h'rizontalfposition 'upwardly in a vertical plane, a boom extension telescopically mounted in the outer end of said boom support and provided at its outer end with a pulley |for ya cable, a double -acting hydraulic cylinder connected between sai-d boom support and said boom extension for extending and retracting the boom extension relative to the boom support, said double acting cylinder being disposed in said boom support and boom extension, said boom support and boom extension comprising telescopic tubular bodies of rect-angular cross section, a cable winch and a hydraulic motor having a rotatable motor shaft for operating the Winch mounted rat the rear end of the iboom support, a cable extending from the winch to the pulley and being guided `and supported on the boom support between the winch and the pulley, and a double acting hydraulic cylinder disposed in approximately a vertical position under said boom support and connecting the boom support and said crane frame for swinging the boom support up and down in -said vertical plane, Ia hydraulic motor for rotating the crane frame relative to the base frame, means for supplying hydraulic medium under pressure, and manually controllable valves for controlling the application of said medium to said cylinders and to said motors to produce motion in each of said motors Iand said cylinders in the forward or backward direction selectively.

6. The combination of claim 5 wherein said winch and its ldriving motor are mounted on the end of the boom support to the rear of said horizontal pivot, and substantially even with the top of the boom support whereby they do not substantially increase the clearance height of the boom support when the 'boom support is substantially horizontal.

7. The combination of claim 5 wherein the said vertical -cylinder is disposed on the crane ltrarne between the said vertical axis thereof and the horizontal pivot for the boom support.

8. The combination of claim 5 wherein the double 'acting extension actuating cylinder is connected at approximately its midpoint to the boom extension by la coupling allowing limited universal movement.

9. The combination of claim 5 wherein hydraulic medium under pressure is supplied to the winch operating motor and to the double acting cylinder in the boom support through separate control valves disposed adjacent to each other, and handles for said control valves disposed to permit operation of both said valves simultaneously by the operator.

l0. The combination of claim 9 wherein the operation of both handles in one direction tends to -admit pressure medium to the boom cylinder to extend the boom extension and to the winch motor to pay out cable, and `operation of 'both handles in the opposite direction tends to admit pressure to the boom cylinder to retract the boom extension and to the winch motor to take up cable.

1l. In a device of the class described, a boom support having a horizontal pivot adjacent its rear end for vertical swinging motion, and having la tubular body of rectangular cross section open at its front end, a boom extension having a tubular 'body of rectangular cross section open at its rear end telescoping inside Isaid boom support, a double acting cylinder disposed inside the boom extension and connected thereto by ya swiveling connection so as to avoid binding in the inward and outward travel with the boom extension, said cylinder having a piston and a piston rod connecting the piston to the rear end of the boom support, said piston rod having two longitudinal passageways therethrough for conducting hydraulic medium to and -from each side of the piston, and hose connections communicating with said passageways at the end of the piston rod adjacent the horizontal pivot.

(References on following page) l References Cited inthe le of this lpartent UNITED STATES PATENTS 'Kilgore Oct. 5, 1897 Speer Apr. 15, 1902 Carey Mar. .'8, 1'910 Petersen Apr. 25, 1911 Baker Oct. 19, 1926 Bureau Nov. 25, 1930 Peters et a1. Aug. 6, 1935 10 Man'ly Apr. 6, 1937 Oldenkamp July 20, 1954 

